Electronic test equipment, such as oscilloscopes, depends on probes to receive input signals to be analyzed. Conventional AC/DC current probes, in particular, utilize split core configuration. A split core configuration is one in which a magnetic field sensor, such as a Hall Effect sensor, works in conjunction with a ferrite core which concentrates the flux field. The ferrite core is split into two parts, so that the ferrite core can be opened and closed, enabling insertion of a conductor carrying the current to be measured.
Although split core probes may be reliable, they tend to be physically large in order to achieve the opening and closing feature, and thus conventional split core probes are substantially limited to larger targets, currents, conductors, and the like. For example, because the current probes are disproportionately large compared to the device under test (DUT), they create a mechanical burden on the DUT itself. More particularly, conventional current probes incorporate a loop of wire that is connected to the DUT, through which the measured current passes. A split core type current probe has a movable jaw that opens and closes around the loop of wire. This movable jaw configuration adds additional bulk to the current probe, and also increases manufacturing costs. Additionally, the large current probes can be position sensitive, so that movement of the current probes causes variations in measurements. Measurement results are thus not repeatable or otherwise inconsistent with respect to one another. Additionally, since split core probes allow the user to control the size and orientation of the current path through the split core, they suffer some repeatability issues.
Some conventional current probes are fixed core type, which do not include the movable jaws, and which are smaller and less costly than the split core type current probes. However, such current probes require that the wire carrying the measured current be threaded through an opening of the current probe. Thus, the use model requires that the wire be unsoldered in order to relocate the current probe from point to point on the DUT, which in turn requires that power be removed from the circuit. For example, the steps for using a conventional, fixed core type current probe generally include turning off the power to the DUT, unsoldering the wire from the circuit, threading the wire through the current probe, soldering the wire to the circuit, and applying power to the DUT. Of course, these same steps must be repeated every time the current probe is moved to another location or removed from the circuit.
Use of any type of conventional current probes typically involves physically cutting a conductive trace, e.g., on a printed circuit board, of the DUT. A wire is then soldered to each end of the cut trace, and the current probe is used to measure current passing through the soldered wire. The properties and position of the soldered wire affect the accuracy and repeatability of the measurement. For example, the length, width, shape (e.g., coiled) and orientation of the soldered wire all factor into the measurement result. Therefore, if any of these variables change between measurements, the results will not be repeatable or otherwise consistent with respect to one another.